Conventional syringe devices, such as those adapted to be operably engaged with power injector devices, are designed to provide metered amounts of a particular therapeutic and/or diagnostic compound to a patient via needle, tube, catheter, and/or other conduit that may be operably engaged with a distal end of the syringe device. Conventional syringe devices provide a piston assembly that is movable between a distal end of the syringe device and a proximal end of the syringe device. Because the piston assembly is often engaged with an interior sidewall of the syringe reservoir in a substantially air-tight engagement (via one or more wiper seals, for example), the retraction of the piston assembly (towards the proximal end of the syringe assembly) may generate a substantial vacuum within the syringe assembly. The generation of a vacuum within a syringe assembly may be caused, for example, when a distal aperture (and/or a conduit downstream of such a distal aperture) defined in the syringe device, is partially or completely occluded (in some cases, by a closed check valve disposed downstream of the distal end of the syringe device).
For example, in some conventional contrast injection devices, a disposable syringe device may be operably engaged with the injection device. The injection device may be capable of automatically retracting the piston assembly to a “replace syringe” position near a proximal end of the syringe device such that the syringe device may be removable from the injection device to facilitate disposal and/or replacement of the syringe device. In some such devices, the movement of the piston assembly to the “replace syringe” position causes the injection device to automatically disengage from the piston assembly when the piston assembly reaches the proximal end of the syringe assembly. Thus, if a substantial vacuum has been created in the syringe device, the force of the vacuum may rapidly (and sometimes violently) draw the piston assembly towards the distal end of the syringe assembly when the injection device disengages the piston assembly. The resulting “piston slap” may, in turn, be violent enough to crack and/or shatter a portion of the syringe device.
Thus, there exists a need in the art for a “vented” or “self-venting” syringe assembly that is capable of relieving the vacuum generated in conventional syringe devices when, for example, a distal end of the syringe device is occluded during retraction of the piston assembly within the syringe. There further exists a need in the art for a disposable “vented” syringe that may be easily manufactured without adding substantial cost to the syringe device.